Nitrogen adsorption via charge transfer on vacancies created during surfactant assisted exfoliation of TiB2

Abstract

Titanium diboride (TiB2), a layered ceramic material, comprised of titanium atoms sandwiched in between honeycomb planes of boron atoms, exhibits a promising structure to utilize the rich chemistry offered by the synergy of titanium and boron. TiB2 has been primarily investigated and applied in its bulk form. This perspective is, however, fast evolving with a number of efforts aimed at exfoliating TiB2. Here, we show that it is possible to delaminate TiB2 into ultrathin, minimally functionalized nanosheets with the aid of surfactants. These nanosheets exhibit crystalline nature and their chemical analysis reveals vacant sites within the nanosheets. These vacancies facilitate the chemisorption of N2 onto the TiB2 nanosheets under ambient conditions without the aid of any energy, this finding was unexpected. This remarkable activity of TiB2 nanosheets is attributed to vacancies and the Ti-B synergy, which enhance the adsorption and activation of N2. We obtained supplemental insights into the N2 adsorption by Density Functional Theory (DFT) studies, which reveal how charge transfer among Ti, B, and N2 results in N2 adsorption. The DFT studies also show that nanosheets having more vacancies result in increased adsorption when compared with nanosheets having less vacancies and bulk TiB2.